virginia密码加密解密，随机产生密钥进行加密。并分别统计了明文和密文中字幕出现的频率，分别对明文和密文进行了重合指数的计算。

运行时，需要把装有明文的in.txt放在程序的同一目录下，并且明文不支持符号，数字，只支持字母-virginia password encryption and decryption, randomly generated keys for encryption. And, respectively, the statistics clearly and subtitles ciphertext in the frequency, respectively, expressly and ciphertext of a coincidence index calculations. Run-time, need to be equipped with an express in.txt on the procedures under the same directory, and expressly does not support the symbols, numbers, letters only support